Diagnosis of spinal infections caused by fastidious bacteria: a multicenter, retrospective observational study.

Abstract

Background context: Identifying pathogens in pyogenic spinal infections is essential for guiding clinical treatment. However, the fastidious characteristics of certain bacteria often make traditional microbial culture methods ineffective, resulting in diagnostic delays and postponed intervention. In recent years, metagenomic next-generation sequencing (mNGS) has shown strong potential in analyzing complex microbial communities, offering a more advanced strategy for pathogen detection.

Purpose: Evaluating mNGS versus microbial culture for diagnosing fastidious bacteria in pyogenic spinal infections.

Study design: A multicenter, retrospective observational study.

Patient sample: We retrospectively reviewed clinical data from 553 patients diagnosed with spinal infections across four medical centers between December 2019 and December 2024.

Outcome measures: Identification of fastidious bacteria in patients.

Methods: All patients underwent imaging and standard laboratory testing. Specimens from infected sites obtained through puncture or surgery were analyzed using both microbial culture and mNGS. According to predefined diagnostic, inclusion, and exclusion criteria for fastidious bacteria, 49 patients (8.86%, 49/553) were identified with pyogenic spinal infections caused by fastidious organisms. We compared the diagnostic outcomes of mNGS with those of culture-based methods for detecting fastidious bacterial pathogens in spinal infections.

Results: Among the 49 patients, mNGS yielded a positive detection rate of 87.76% (43/49), which was significantly higher than that of conventional culture methods at 16.33% (8/49) (χ²=12.683, p < 0.001). Among the 41 culture-negative cases, mNGS successfully identified fastidious bacteria in 37, corresponding to an effective supplementary detection rate of 90.24% (37/41). While culture identified 5 species of fastidious bacteria, mNGS detected 15, giving an effective pathogen supplementation rate of 66.7% (10/15). These 15 bacteria fell into two groups: the first included those that cannot be cultured using routine clinical media (26/43, 60.47%), and the second included those that may sporadically grow in standard cultures but tend to show low positivity (17/43, 39.53%). Out of the total 553 cases, 382 were culture-negative. Among these, 37 (37/382, 9.69%) were identified as fastidious bacteria via mNGS. mNGS yielded results within 48 hours, significantly faster than the 3-7 days typically required by culture methods.

Conclusions: In cases of pyogenic spinal infections caused by fastidious bacteria, mNGS demonstrated a higher detection rate, wider pathogen range, and significantly shorter turnaround compared to traditional microbial culture. The culture-independent approach of mNGS presents a distinct advantage in identifying fastidious pathogens.